12kV/24kV Solid Insulated Ring Main Unit
✅Highly Environmentally Friendly
✅Fully Insulated and Fully Sealed,IP67
✅Compact Structure and Small Footprint
✅Maintenance‑Free and Long Service Life
✅Modular Design: Flexible expansion
- Product Introduction
The 12kV / 24kV solid-insulated ring main unit (SIS RMU) is a mainstream, advanced solution in modern medium-voltage power distribution networks.
Designed for safety and reliability, this 12kV / 24kV solid-insulated ring main unit features a fully enclosed structure where all high-voltage live parts-including busbars, switches, and circuit breakers-are completely encapsulated and sealed using high-grade epoxy resin or other advanced solid insulating materials.
Main Features
Solid Insulation System：Unlike traditional Air-Insulated Switchgear (AIS) that relies on air gas, or SF6 Gas-Insulated Switchgear (GIS) that relies on sulfur hexafluoride gas, this 12kV / 24kV solid-insulated ring main unit utilizes high-grade solid epoxy resin as its primary insulating medium.
Fully Encapsulated & Sealed Design：All live high-voltage components are completely encapsulated within solid insulation material, forming a robust, fully sealed, and maintenance-free modular unit.
Compact Footprint & Environmental Sustainability：Combining a space-saving modular design with zero SF6 gas emissions, this equipment delivers an eco-friendly footprint perfectly suited for space-constrained installations.
Structure Features
Advanced Insulating Medium: Utilizes high-grade epoxy resin as the primary insulating material, delivering exceptional dielectric strength, superior mechanical durability, and long-term thermal aging resistance.
Modular Structural Design: Each functional unit (such as load switches or circuit breakers) is an independent, fully sealed solid-insulated module. These modules feature plug-in busbar connectors, achieving a completely enclosed and expandable busbar system.
Ergonomic Operating Mechanism: The front-mounted operating mechanism connects to internal moving contacts via sealed insulating drive rods, enabling smooth and reliable opening and closing operations.
Integrated Three-Position Switch: The load-switch module features an integrated three-position design-"Closed" (Connect), "Open" (Disconnect), and "Earthed" (Earth)-with clear mechanical interlocking to ensure maximum operator safety and simplified maintenance.
Technical Parameters
| No. | Item | Unit | Parameters | |||
| 12kV | 24kV | |||||
| 1 | Rated Voltage | kV | 12 | 24 | ||
| 2 | Rated Current | A | 630 | 1250 | 630 | |
| 3 | Rated Frequency | Hz | 50/60 | 50/60 | ||
| 4 | Rated Power Frequency Withstand Voltage 1 min | kV | 48 | 50 | 65 | |
| 5 | Rated Lightning Impulse Withstand Voltage | kV | 85 | 125 | 125 | |
| 6 | Rated Short-time Withstand Current | kA/S | 20/4 | 25/4 | 20/4 | 20/4 |
| 7 | Rated Breaking Current | kA | 20 | 25 | 16/20 | 20 |
| 8 | Rated Short Circuit Making Current (Peak) | kA | 50 | 62.5 | 40/50 | 50 |
Comparison with Mainstream RMU Types
| Characteristic | Solid Insulated RMU | SF₆ Gas‑Insulated RMU | Sealed Air‑Insulated RMU (Atmospheric Pressure) | Traditional Air‑Insulated RMU |
|---|---|---|---|---|
| Insulating Medium | Solid Epoxy Resin | SF₆ Gas | Dry Air | Ambient Air |
| Environmental Friendliness | Excellent (no greenhouse gases) | Poor (SF₆ is a potent greenhouse gas) | Excellent (no SF₆) | Excellent |
| Size | Small (modular, compact) | Smallest (good gas insulation) | Medium | Largest (requires large insulation distances) |
| Environmental Impact | Unaffected by humidity, condensation, contamination | Unaffected by external environment | Basically unaffected | Susceptible to condensation, contamination, pests |
| Safety | High (fully insulated, no risk of ignition/explosion) | High | High | Relatively low (exposed live parts) |
| Maintenance | Maintenance‑free (fully sealed) | Requires pressure monitoring; leaks must be handled | Maintenance‑free | Requires periodic cleaning, dehumidification |
| Cost | Relatively high (complex process) | High (stringent gas‑handling requirements) | Medium | Lowest |
| Market Trend | Mainstream development direction, policy‑encouraged | Restricted by environmental regulations, being phased out | Important complementary technology, rapidly developing | Traditional solution, still used in specific applications |
Application Scenarios
Application Scenarios
Coastal & Marine Environments
Features a fully sealed operating mechanism tested in professional high-salt-spray chambers to ensure long-term, corrosion-resistant performance in harsh coastal atmospheres.
Low-Temperature Regions
Eliminates SF6 gas entirely, avoiding the risk of insulation degradation or pressure drops caused by gas liquefaction in extremely cold climates.
High-Altitude & Plateau Regions
Free from internal gas pressure constraints, preventing the risk of tank deformation or seal failure caused by extreme atmospheric pressure differentials at high elevations.
Explosion-Prone Environments
Uses vacuum interrupters fully encapsulated within solid epoxy resin bushings, effectively eliminating gas exposure risks and preventing potential explosions.
Frequent Switching Duty
Designed for high-frequency operations, achieving a mechanical endurance of up to 20,000 switching cycles for long-term operational reliability.
Eco-Sensitive & SF₆-Free Zones
Completely SF6-free, directly supporting global carbon reduction initiatives by eliminating potent greenhouse gas emissions.
Windy, Dusty & Sandy Conditions
Engineered with an IP67 protection rating for all high-voltage live parts and specialized sealing for the control compartment, ensuring continuous operation in desert and dusty environments.
High-Temperature Conditions
Rigorously heat-chamber tested to operate reliably in ambient temperatures reaching up to +70°C, making it ideal for extreme tropical or desert installations.
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